Light curing apparatus and techniques, as have been used in dental applications to date, have been directed primarily to the use of light curing of restorative materials, such as in oral cavities. In such applications, which have been reasonably successful, a light source is positioned at or substantially at contact with the material to be cured, such that a highly focused or condensed beam of light is directed on a relatively small area of curable material. For example, assignee's Prisma Lite system employs a light gun, or applicator as shown in U.S. Pat. No. 4,385,344. Prior to this visible light application, UV curable materials and UV sources had been used in the dental industry. Generally, the applications have been limited to small localized fillings and the like.
In the field of fabricating dentures, little work has been done heretofore in the use of light polymerizable or curable materials. However, recent technique and material developments for dental prosthetic and restorative work, have made it feasible to produce dentures much more quickly and reliably than has been done in the prior art. These new techniques and methods for making artificial teeth, can be used by dentists and/or dental laboratories to fabricate dentures and restorations.
The operation of light curing a denture or prosthetic bridge presents certain problems which are not encountered using more conventional methods. However, once solved the light curing operation permits a much more efficient denture making process. Any satisfactory apparatus for light curing of dentures requires a substantial depth and degree of curing, much more than for curing coatings. Dentures come in vastly different sizes and shapes, and the penetration requirements vary with the size and configuration. A standarized light source apparatus for curing dentures needs to provide light of an intensity to be safely above the zone of reciprocity failure, i.e., the zone below which curing is not achieved no matter how long light is applied. Further, an apparatus and method is needed which ensures that light is incident at all possible angles onto all features of the denture, so that all portions of the material are light penetrated and cured. Thus, there is a great demand placed upon any proposed apparatus and technique for photocuring a wide range of sizes and shapes of restorative objects, which apparatus must be safe for people working in the immediate area, and which must operate with a sufficient efficiency to minimize apparatus bulk and expense, thereby ensuring low maintenance and maximum reliability of operation. With the provision of such apparatus, dentures can be cured in a matter of minutes, which is a highly substantial advance over the prior capability of the industry.